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From: Jason Gunthorpe <jgg@nvidia.com>
To: "Raj, Ashok" <ashok.raj@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Dan Williams <dan.j.williams@intel.com>,
	"Tian, Kevin" <kevin.tian@intel.com>,
	"Jiang, Dave" <dave.jiang@intel.com>,
	Bjorn Helgaas <helgaas@kernel.org>,
	"vkoul@kernel.org" <vkoul@kernel.org>,
	"Dey, Megha" <megha.dey@intel.com>,
	"maz@kernel.org" <maz@kernel.org>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
	"Liu, Yi L" <yi.l.liu@intel.com>,
	"Lu, Baolu" <baolu.lu@intel.com>,
	"Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
	"Luck, Tony" <tony.luck@intel.com>,
	"kwankhede@nvidia.com" <kwankhede@nvidia.com>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	"parav@mellanox.com" <parav@mellanox.com>,
	"rafael@kernel.org" <rafael@kernel.org>,
	"netanelg@mellanox.com" <netanelg@mellanox.com>,
	"shahafs@mellanox.com" <shahafs@mellanox.com>,
	"yan.y.zhao@linux.intel.com" <yan.y.zhao@linux.intel.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"Ortiz, Samuel" <samuel.ortiz@intel.com>,
	"Hossain, Mona" <mona.hossain@intel.com>,
	"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH v4 06/17] PCI: add SIOV and IMS capability detection
Date: Tue, 10 Nov 2020 10:19:00 -0400	[thread overview]
Message-ID: <20201110141900.GO2620339@nvidia.com> (raw)
In-Reply-To: <20201110051412.GA20147@otc-nc-03>

On Mon, Nov 09, 2020 at 09:14:12PM -0800, Raj, Ashok wrote:

> There are multiple tools (such as logic analyzers) and OEM test validation 
> harnesses that depend on such DWORD sized DMA writes with no PASID as interrupt
> messages. One of the feedback we had received in the development of the
> specification was to avoid impacting such tools irrespective of
> MSI-X or IMS

This is a really bad reason to make a poor decision for system
security. Relying on trapping/emulation increases the attack surface
and complexity of the VMM and the device which now have to create this
artificial split, which does not exist in SRIOV.

Hopefully we won't see devices get this wrong, but any path that
allows the guest to cause the device to create TLPs outside its IOMMU
containment is security worrysome.

> was used for interrupt message storage (on the wire they follow the
> same format), and also to ensure interoperability of devices
> supporting IMS across CPU vendors (who may not support PASID TLP
> prefix).  This is one reason that led to interrupts from IMS to not
> use PASID (and match the wire format of MSI/MSI-X generated
> interrupts).  The other problem was disambiguation between DMA to
> SVM v/s interrupts.

This is a defect in the IOMMU, not something fundamental.

The IOMMU needs to know if the interrupt range is active or not for
each PASID. Process based SVA will, of course, not enable interrupts
on the PASID, VM Guest based PASID will.

> Intel had published the specification almost 2 years back and have
> comprehended all the feedback received from the ecosystem 
> (both open-source and others), along with offering the specification 
> to be implemented by any vendors (both device and CPU vendors). 
> There are few device vendors who are implementing to the spec already and 
> are being explored for support by other CPU vendors

Which is why it is such a shame that including PASID in the MSI was
deliberately skipped in the document, the ecosystem could have been
much aligned to this solution by now :(

Jason

  parent reply	other threads:[~2020-11-10 14:19 UTC|newest]

Thread overview: 125+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-30 18:50 [PATCH v4 00/17] Add VFIO mediated device support and DEV-MSI support for the idxd driver Dave Jiang
2020-10-30 18:50 ` [PATCH v4 01/17] irqchip: Add IMS (Interrupt Message Store) driver Dave Jiang
2020-10-30 22:01   ` Thomas Gleixner
2020-10-30 18:51 ` [PATCH v4 02/17] iommu/vt-d: Add DEV-MSI support Dave Jiang
2020-10-30 20:31   ` Thomas Gleixner
2020-10-30 20:52     ` Dave Jiang
2020-10-30 18:51 ` [PATCH v4 03/17] dmaengine: idxd: add theory of operation documentation for idxd mdev Dave Jiang
2020-10-30 18:51 ` [PATCH v4 04/17] dmaengine: idxd: add support for readonly config devices Dave Jiang
2020-10-30 18:51 ` [PATCH v4 05/17] dmaengine: idxd: add interrupt handle request support Dave Jiang
2020-10-30 18:51 ` [PATCH v4 06/17] PCI: add SIOV and IMS capability detection Dave Jiang
2020-10-30 19:51   ` Bjorn Helgaas
2020-10-30 21:20     ` Dave Jiang
2020-10-30 21:50       ` Bjorn Helgaas
2020-10-30 22:45       ` Jason Gunthorpe
2020-10-30 22:49         ` Dave Jiang
2020-11-02 13:21           ` Jason Gunthorpe
2020-11-03  2:49             ` Tian, Kevin
2020-11-03 12:43               ` Jason Gunthorpe
2020-11-04  3:41                 ` Tian, Kevin
2020-11-04 12:40                   ` Jason Gunthorpe
2020-11-04 13:34                     ` Tian, Kevin
2020-11-04 13:54                       ` Jason Gunthorpe
2020-11-06  9:48                         ` Tian, Kevin
2020-11-06 13:14                           ` Jason Gunthorpe
2020-11-06 16:48                             ` Raj, Ashok
2020-11-06 17:51                               ` Jason Gunthorpe
2020-11-06 23:47                                 ` Dan Williams
2020-11-07  0:12                                   ` Jason Gunthorpe
2020-11-07  1:42                                     ` Dan Williams
2020-11-08 18:11                                     ` Raj, Ashok
2020-11-08 18:34                                       ` David Woodhouse
2020-11-08 23:25                                         ` Raj, Ashok
2020-11-10 14:19                                           ` Raj, Ashok
2020-11-10 14:41                                             ` David Woodhouse
2020-11-08 23:41                                       ` Jason Gunthorpe
2020-11-09  0:05                                         ` Raj, Ashok
2020-11-08 18:47                                     ` Thomas Gleixner
2020-11-08 19:36                                       ` David Woodhouse
2020-11-08 22:47                                         ` Thomas Gleixner
2020-11-08 23:29                                           ` Jason Gunthorpe
2020-11-11 15:41                                         ` Christoph Hellwig
2020-11-11 16:09                                           ` Raj, Ashok
2020-11-11 22:27                                             ` Thomas Gleixner
2020-11-11 23:03                                               ` Raj, Ashok
2020-11-12  1:13                                                 ` Thomas Gleixner
2020-11-12 13:10                                                 ` Jason Gunthorpe
2020-11-08 23:23                                       ` Jason Gunthorpe
2020-11-08 23:36                                         ` Raj, Ashok
2020-11-09  7:37                                         ` Tian, Kevin
2020-11-09 16:46                                           ` Jason Gunthorpe
2020-11-08 23:58                                       ` Raj, Ashok
2020-11-09  7:59                                         ` Tian, Kevin
2020-11-09 11:21                                         ` Thomas Gleixner
2020-11-09 17:30                                           ` Jason Gunthorpe
2020-11-09 22:40                                             ` Raj, Ashok
2020-11-09 22:42                                             ` Thomas Gleixner
2020-11-10  5:14                                               ` Raj, Ashok
2020-11-10 10:27                                                 ` Thomas Gleixner
2020-11-10 14:13                                                   ` Raj, Ashok
2020-11-10 14:23                                                     ` Jason Gunthorpe
2020-11-11  2:17                                                       ` Tian, Kevin
2020-11-12 13:46                                                         ` Jason Gunthorpe
2020-11-11  7:14                                                     ` Tian, Kevin
2020-11-12 19:32                                                       ` Konrad Rzeszutek Wilk
2020-11-12 22:42                                                         ` Thomas Gleixner
2020-11-13  2:42                                                           ` Tian, Kevin
2020-11-13 12:57                                                             ` Jason Gunthorpe
2020-11-13 13:32                                                             ` Thomas Gleixner
2020-11-13 16:12                                                               ` Luck, Tony
2020-11-13 17:38                                                                 ` Raj, Ashok
2020-11-14 10:34                                                           ` Christoph Hellwig
2020-11-14 21:18                                                             ` Raj, Ashok
2020-11-15 11:26                                                               ` Thomas Gleixner
2020-11-15 19:31                                                                 ` Raj, Ashok
2020-11-15 22:11                                                                   ` Thomas Gleixner
2020-11-16  0:22                                                                     ` Raj, Ashok
2020-11-16  7:31                                                                       ` Tian, Kevin
2020-11-16 15:46                                                                         ` Jason Gunthorpe
2020-11-16 17:56                                                                           ` Thomas Gleixner
2020-11-16 18:02                                                                             ` Jason Gunthorpe
2020-11-16 20:37                                                                               ` Thomas Gleixner
2020-11-16 23:51                                                                               ` Tian, Kevin
2020-11-17  9:21                                                                                 ` Thomas Gleixner
2020-11-16  8:25                                                               ` Christoph Hellwig
2020-11-10 14:19                                                 ` Jason Gunthorpe [this message]
2020-11-11  2:35                                                   ` Tian, Kevin
2020-11-08 21:18                             ` Thomas Gleixner
2020-11-08 22:09                               ` David Woodhouse
2020-11-08 22:52                                 ` Thomas Gleixner
2020-11-07  0:32                           ` Thomas Gleixner
2020-11-09  5:25                             ` Tian, Kevin
2020-10-30 18:51 ` [PATCH v4 07/17] dmaengine: idxd: add IMS support in base driver Dave Jiang
2020-10-30 18:51 ` [PATCH v4 08/17] dmaengine: idxd: add device support functions in prep for mdev Dave Jiang
2020-10-30 18:51 ` [PATCH v4 09/17] dmaengine: idxd: add basic mdev registration and helper functions Dave Jiang
2020-10-30 18:51 ` [PATCH v4 10/17] dmaengine: idxd: add emulation rw routines Dave Jiang
2020-10-30 18:52 ` [PATCH v4 11/17] dmaengine: idxd: prep for virtual device commands Dave Jiang
2020-10-30 18:52 ` [PATCH v4 12/17] dmaengine: idxd: virtual device commands emulation Dave Jiang
2020-10-30 18:52 ` [PATCH v4 13/17] dmaengine: idxd: ims setup for the vdcm Dave Jiang
2020-10-30 21:26   ` Thomas Gleixner
2020-10-30 18:52 ` [PATCH v4 14/17] dmaengine: idxd: add mdev type as a new wq type Dave Jiang
2020-10-30 18:52 ` [PATCH v4 15/17] dmaengine: idxd: add dedicated wq mdev type Dave Jiang
2020-10-30 18:52 ` [PATCH v4 16/17] dmaengine: idxd: add new wq state for mdev Dave Jiang
2020-10-30 18:52 ` [PATCH v4 17/17] dmaengine: idxd: add error notification from host driver to mediated device Dave Jiang
2020-10-30 18:58 ` [PATCH v4 00/17] Add VFIO mediated device support and DEV-MSI support for the idxd driver Jason Gunthorpe
2020-10-30 19:13   ` Dave Jiang
2020-10-30 19:17     ` Jason Gunthorpe
2020-10-30 19:23       ` Raj, Ashok
2020-10-30 19:30         ` Jason Gunthorpe
2020-10-30 20:43           ` Raj, Ashok
2020-10-30 22:54             ` Jason Gunthorpe
2020-10-31  2:50             ` Thomas Gleixner
2020-10-31 23:53               ` Raj, Ashok
2020-11-02 13:20                 ` Jason Gunthorpe
2020-11-02 16:20                   ` Raj, Ashok
2020-11-02 17:19                     ` Jason Gunthorpe
2020-11-02 18:18                       ` Dave Jiang
2020-11-02 18:26                         ` Jason Gunthorpe
2020-11-02 18:38                           ` Dan Williams
2020-11-02 18:51                             ` Jason Gunthorpe
2020-11-02 19:26                               ` Dan Williams
2020-10-30 20:48 ` Thomas Gleixner
2020-10-30 20:59   ` Dave Jiang
2020-10-30 22:10     ` Thomas Gleixner
     [not found] <draft-875z6ekcj5.fsf@nanos.tec.linutronix.de>
2020-11-09 14:08 ` [PATCH v4 06/17] PCI: add SIOV and IMS capability detection Thomas Gleixner
2020-11-09 18:10   ` Raj, Ashok

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